WIP refactor: add remote_poc_test

src/remote/framing.zig

@@ -0,0 +1,36 @@
+const std = @import("std");
+
+pub const max_frame_size = 8 * 4096; // matches thespian.max_message_size
+
+/// Write a length-prefixed frame. writer must support writeAll.
+pub fn write_frame(writer: anytype, payload: []const u8) !void {
+    var len_buf: [4]u8 = undefined;
+    std.mem.writeInt(u32, &len_buf, @intCast(payload.len), .big);
+    try writer.writeAll(&len_buf);
+    try writer.writeAll(payload);
+}
+
+/// Accumulates bytes until a complete length-prefixed frame is available.
+/// Returns a slice into the internal buffer on completion; null if more bytes
+/// are needed. The returned slice is only valid until the next call to feed().
+pub const Accumulator = struct {
+    buf: [max_frame_size + 4]u8 = undefined,
+    pos: usize = 0,
+
+    pub fn feed(self: *Accumulator, bytes: []const u8) ?[]const u8 {
+        const to_copy = @min(bytes.len, self.buf.len - self.pos);
+        @memcpy(self.buf[self.pos..][0..to_copy], bytes[0..to_copy]);
+        self.pos += to_copy;
+
+        if (self.pos < 4) return null;
+
+        const payload_len = std.mem.readInt(u32, self.buf[0..4], .big);
+        if (payload_len > max_frame_size) return null;
+
+        const total = 4 + payload_len;
+        if (self.pos < total) return null;
+
+        self.pos = 0;
+        return self.buf[4..total];
+    }
+};

src/remote/protocol.zig

@@ -0,0 +1,24 @@
+const cbor = @import("cbor");
+
+pub const WireMessage = union(enum) {
+    send_named: SendNamed,
+
+    pub const SendNamed = struct {
+        from_id: u64,
+        to_name: []const u8,
+        payload: []const u8, // raw CBOR bytes
+    };
+};
+
+/// Decode a raw CBOR frame into a WireMessage.
+/// Returned slices point into the frame buffer and are only valid while it lives.
+pub fn decode(frame: []const u8) !WireMessage {
+    var from_id: u64 = 0;
+    var to_name: []const u8 = "";
+    var payload: []const u8 = "";
+
+    if (try cbor.match(frame, .{ "send_named", cbor.extract(&from_id), cbor.extract(&to_name), cbor.extract_cbor(&payload) }))
+        return .{ .send_named = .{ .from_id = from_id, .to_name = to_name, .payload = payload } };
+
+    return error.UnknownMessageType;
+}